Technical Field
The present invention relates to an operation handle mechanism for moving and operating a movable part, and, for example, to an operation handle mechanism suitably used to move and operate a load in a support mechanism, which supports the load such as articles in a movable manner, as well as to a load support mechanism.
Background Art
Conventionally, in a support mechanism that supports a computer, a television monitor device, and various other articles in such a way as to be able to move the articles up and down to a desired height position, an operation handle is often provided to manually operate the movement of the articles. For example, what is known is an elevating blackboard equipped with a pair of left and right manual handles for elevating, which are located around the left and right sides of the center in a horizontal lower portion of a support frame (Refer to Patent Document 1 [Jpn. Pat. Appln. Laid-Open Publication No. 11-137362], for example).
The blackboard disclosed in Patent Document 1 is held in such a way as to be able to move up and down, as vertical poles on the left and right sides of the support frame are inserted into up-down guide holes of a fixed frame. Furthermore, the left- and right-end areas of the lower portion of the support frame are supported in such a way as to be lifted up by two wires, which are connected to an outer periphery of a common drum, and by a spring means, which is connected to a cam of the drum. Accordingly, the support frame can be stopped at any given height, as the weight of the blackboard is absorbed.
A sheet supply device is also known (Refer to Patent Document [Jpn. Pat. Appln. Laid-Open Publication No. 2003-276953], for example): the sheet supply device supplies a sheet to an image formation device such as a copier by driving a lifting motor and thereby moving a sheet placement table up and down. In this device, a lifting gear that is fixed to a motor shaft of the lifting motor, and another lifting gear of the same shape that is engaged with the lifting gear, are engaged with left and right lifting racks that are provided on the sheet placement table. Therefore, the sheet placement table of a relatively large planar size can vertically move up and down while being in a horizontal state.
However, if a user stands by the left or right end portion of the above-described conventional elevating blackboard, the user needs to move to around the left and right sides of the center of the blackboard where the manual handles are provided each time the user tries to move the blackboard up and down. Therefore, this configuration is inconvenient. One of improvement measures would be to provide additional manual handles in the left- and right-end areas of the blackboard, if an article that is long in the left-right direction, such as an elevating blackboard, should be moved up and down.
However, if an operation force is applied only to either the left or right side of the support frame of the support mechanism of such an article, the support frame might be distorted or twisted due to the weight of the article, the structure or strength of the support frame, the magnitude of the operation force, and the like. The distortion or twisting of the support frame is not preferred as it can cause troubles such as backlash when the article is moved up or down and hamper a smooth movement operation and operation of lifting up and down.
Another improvement measure is to provide a handle that is long in the left-right direction. However, the problem is that, if the handle is a long rod-shaped handle that extends in a direction that crosses the operation direction or the direction in which the article is moved, and if the operation force is concentrated on one end portion, the handle would be easily bent in the operation direction unless the rigidity of the handle is sufficiently high. In this case, depending on which area of the handle is operated, the operation force would act on the support frame unevenly in the left-right direction, leading to similar distortion or twisting of the support frame and possibly unable to ensure a smooth movement operation and operation of lifting the article up and down.